Chondrichthyes

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The Narrownose chimaera (Harriotta raleighana), occurs in deep waters of the continental slopes in depths of 380 to 2,600 m in both the Atlantic and Pacific Oceans.  They are oviparous but nothing is known of spawning and reproduction and very few juveniles have been collected. It was filmed swimming 10 m above the seafloor in Hydrographer Canyon, off the coast of Nantucket Island in the US.

Species in the Rhinochimaera family are known as long-nosed chimaeras. Their unusually long snouts (compared to other chimaeras) have sensory nerves that allow the fish to find food. Also, their first dorsal fin contains a mildly venomous spine that is used defensively. They are found in deep, temperate and tropical waters between 200 to 2,000 m in depth, and can grow to be up to 140 cm (4.5 ft) in length.

Chimaeras (also known as ghost sharks and ratfish) are an order of cartilaginous fish most closely related to sharks, but they have been evolutionarily isolated from them for over 400 million years.

(Info from WP and .gif from video by NOAA's Okeanos Explorer—this is not an animation!)

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Blacktip Reef Shark (Carcharhinus melanopterus)

Photos taken by me - Tioman Island, Malaysia. 

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Angular Roughshark (Oxynotus centrina)

…is a species of rough shark found throughout the eastern Atlantic, from Norway all the way down to South Africa. Unlike other rough sharks this species has ridges over its eyes, these ridges extend to knobs which are covered with scales. Angular roughsharks are usually found on muddy or algal bottoms of continental shelves where they feed on invertebrates like molluscs and arthropods.

Phylogeny

Animalia-Chordata-Chondrichthyes-Elasmobranchii-Squaliformes-Oxynotidae-Oxynotus-centrina

Image Source(s)

Just before a shark breaks the surface tension of the water

I came across this photo while perusing the good ol’ internet a few weeks ago, and now that I’m back from a mildly extended absence, I still want to share it. This image is stunning, to say the least. In my opinion, it shows off just how beautiful and mysterious these creatures are. It’s these minute glimpses into their environment and lives that captivates and motivates me to continue my studies.

Banjo Shark - Montague Island | ©Rowland Cain  (Montague Island, New South Wales, Australia)

The Banjo shark or Fiddler ray, genus Trygonorrhina, are guitarfish in the family Rhinobatidae and order Rajiformes.

Banjo sharks are actually shark-like ray with disc flattened, oval to diamond-shaped; snout short, broadly triangular; row of large thorn-like denticles along the middle of the back; yellowish-brown above with dark-edged greyish bands radiating from the eyes and on either sides of back; lower caudal-fin lobe poorly-defined; and no distinct triangular or diamond-shaped marking behind eyes [1].

There are two species of banjo sharks found along the eastern and southern coasts of Australia [2].

February on this blog is going to be Daily Paleo Art Month! Because doing dinosaurs all last July was so much fun I want to do this thing again.
 Every weekday for the rest of the month I’ll be posting a new image of something strange, obscure, or just plain interesting from the fossil record – only this time we’re staying firmly outside of the Avemetatarsalia (pterosaurs and dinosaurs/birds) to give some less famous critters the spotlight.

#1: Helicoprion

A cartilaginous fish from off the southwest coast of the ancient supercontinent Gondwana (and later Pangaea), Helicoprion first appeared in the late Carboniferous (310 million years ago) and survived up until just past the massive Permian-Triassic extinction (250mya). Despite looking rather shark-like and possibly reaching sizes of around 6m (20ft) long, it was actually closer related to the chimaeras.

For a long time, the only parts of this animal known were bizarre buzzsaw-like spiral whorls of teeth, since cartilage skeletons very rarely fossilize. The ideas for just where in the body this structure was positioned were ridiculously varied.

The most recent reconstruction is based on CT scans of a well-preserved fossil with jaw and skull elements, which showed the whorl taking up the whole lower jaw. It also turns out Helicoprion had no upper teeth at all. It’s thought to have used this arrangement to shred and crush up squid and other soft-bodied marine prey, but there’s still very little known about how such a unique type of teeth evolved in the first place.

Golden Cownose Ray (Rhinoptera steindachneri)

Also known as the Pacific Cownose Ray, the golden cownose ray is a species of eagle ray (Myliobatidae) which occurs in the eastern Pacific, ranging from central Baja California south to Peru and the Galapagos Islands. Golden cownose rays like other eagle rays are a transient and highly mobile species, often forming large schools or moving in loose aggregations. R. steindarchneri feeds mainly on molluscs and other hard bodied invertebrates, using its plate-like teeth which are specialized for crushing and grinding. 

Classification

Animalia-Chordata-Chondrichthyes-Elasmobranchii-Myliobatiformes-Myliobatidae-Rhinoptera-R. steindachneri

Image: Atomische

The Salmon Shark (Lamna ditropis) is often mistaken for juvenile great whites due to their similar body structure and tendency to breach out of the water in pursuit of prey. They’re one of my personal favorite sharks, closely related to the porbeagle shark

Reaching up to 10 feet in length, they’re able to travel through a wide range of depths and temperatures from Japan to Oregon and California, and even Alaska! Of course, being migratory sharks they cross much more water than just those areas. Since they’re homeothermic,  they are able to chase high energy prey including squid, sea otters, sea birds, and possibly even pinnipeds. Alaskan salmon sharks consume anywhere from 12-25% of the annual Pacific Salmon run in Prince William Sound! Unlike many shark species, including the soon-to-be endangered great white, salmon sharks have a stable population as a Least Concern species. Despite this, they still have no more than four to five pups every TWO years, and it can take up to 13 years for them to sexually mature. 

Although there are no known attacks on humans, this shark can still pose a risk to us! Don’t forget your shark safety when entering the waters.

Ocellate River Stingray - Potamotrygon motoro

Potamotrygon motor (Rajiformes - Potamotrygonidae) is a species of freshwater stingray endemic to, and widespread throughout, several South American river systems.

These stingrays can be distinguished from closely related species by the presence of orange to yellow dorsal eyespots, each surrounded by a black ring, with diameters larger than the eyes. Body color is otherwise greyish-brown. They are oval in shape with a robust tail, bearing a venomous spine. Maximum total length has been reported at 100 centimeters and maximum weight at 15 kg, though individuals tend to be much smaller.

Reference: [1]

Photo credit: ©Jason Hering | Locality: Cuiaba river, Matto Grosso, Amazon, Brazil - captive (2008)

Salmon Shark (Lamna ditropis)

….is a species of shark found throughout the north Pacific ocean. As hinted by its name this shark species feeds on large fish like salmon and herring. One of the most interesting features of this shark is its ability regulate its body temperature via a process called Homeothermy. In homeothermy the shark has special a special vascular system called a retia mirabilia this system keeps blood moving towards the sharks extremities flowing next to colder returning blood warming the animal via heat transfer.

Phylogeny

Animalia-Chordata-Chondrichthyes-Elasmobranchii-Lamniformes-Lamnidae-Lamna-ditropis

Image Source(s)

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Hatching Shorttail fanskate (Sympterygia brevicaudata) The capsule from where it left is an egg case or egg capsule, colloquially known as a mermaid’s purse or devil’s purse, is a casing that surrounds the fertilized eggs of some sharks, skates, and chimaeras. Has small openings (respiratory slits) where it enters and leaves the water, so the embryo can breathe…

  • video: Mylene Seguel

Common Thresher Shark - Alopias vulpinus 

The Common Thresher Shark, Alopias vulpinus (Lamniformes - Alopiidae), is a species of shark virtually circumglobal, with a noted tolerance for cold waters. Common thresher sharks weigh 348 kg on average and can reach up to 500 kg. They range from 1.6 to 6 m in length, averaging 2.74 m. Up to 50 % of a thresher’s length is due to the characteristic enlarged upper lobe of its caudal fin. Alopias vulpinus is the largest of the thresher species.

This species is listed as Vulnerable globally because of their declining populations, as these sharks are especially vulnerable to fisheries exploitation (target and by-catch) because its epipelagic habitat occurs within the range of many largely unregulated and under-reported gillnet and longline fisheries, in which it is readily caught. 

References: [1] - [2]

Photo credit: ©Norbert Probst | Locality: Brother Islands. Egypt, Red Sea (2013)

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The Simia marina from the Codex Kentmanus, which Jonathan Couch considered to be a chimera. I would be inclined to agree. Things get weird since Georg Steller claimed to have seen a creature which strongly resembled the Simia marina, but he described a marine mammal of indeterminate species


Kusukawa, S. (2010) The sources of Gessner’s pictures for the Historia animalium. Annals of Science 67(3) 303–328. 

Couch, J. (1877) A History of the Fishes of the British Isles. Volume 1.

Japanese Sawshark (Pristiophorus japonicus)

…a species of sawshark (Pristiophoridae) which occurs in the northwest Pacific Ocean around Japan, Korea, and northern China, where it inhabits the sandy or muddy bottoms of the continental shelves (at depths of 50-800 m). Japanese sawsharks are primarily “benthic” and will feed on a wide range of small bottom dwelling invertebrates and fish. 

Classification

Animalia-Chordata-Chondrichthyes-Elasmobranchii-Pristiophoriformes-Pristiophoridae-Pristiophorus-P. japonicus

Image: Opencago.info